The invention is an intraocular lens with accompanying auxiliary devices by means of which a patient once again gains the capability of optical near vision (accommodation) through and after an operation on the natural lens.
Intraocular lenses which are in accordance with the state of technology normally only allow sharp vision at exactly one distance. In addition, for some years, intraocular lenses have been known which have two or more focal distances (xe2x80x9cmultifocal lensesxe2x80x9d) and thus allow sharp vision at several distances. As several images are hereby superimposed indistinctly, the contrast with these lenses is markedly worse than with a monofocal lens. Also, it is only possible to see sharply at certain distances, the intermediate area is markedly more indistinct. Vision, as in the case of natural accommodation, can thus not be attained with these lenses.
Systems in which the refractive power of the intraocular implant can be adjusted by external measures represent an intermediate notional step towards accommodation. The optical elements can here be shifted on the optical axis by changing the posture of the head, by means of gravity or by magnetic forces (US5326347A, US5593437A). In the latter case, a magnetic layer is applied to the intraocular lens and the lens is moved by an adjustable magnet which is positioned in front of the eye in a kind of spectacles. In US5800533A, the shift on the optical axis is induced by means of a screw thread, whereby the screwing process is carried out by means of magnetic tools from outside of the eye.
The adjustability described above is not sufficient to restore an accommodation capability that is felt by the patient as being xe2x80x9cnaturalxe2x80x9d after the removal of the interior of his own, opaque lens (cataract). Instead, the refractive power of the implanted artificial lens has to be changed, for example, by means of its form or by shifting it along the optical axis, or by shifting several optical elements towards one another when the ciliary muscle contracts. Here below, only this process is intended to be understood under xe2x80x9caccommodationxe2x80x9d. Several approaches have become known for implementing it. A balloon, that can be filled with liquid, can be inserted into the capsular bag (EP0493090A1). Two optically effective components can be shifted towards one another by hydrostatic pressure (IEP0356050B1). Optical components are shifted by means of spring pressure (EP0337390A2). In addition, there are intraocular lenses commercially available, the outer part of which (haptics) is formed as a springy hinge so that a radial contraction is turned into an axial shift (WO9615734A2).
None of the said approaches has been able to gain practical importance up to now. The reason is in principle the same for all of them: After removal of the interior of the lens, a shrinkage and hardening of the capsular bag occurs which differs greatly individually. The capsular bag can thus not be used as an element of a movement process of whatever kind that can be calculated in its mechanical parameters. In addition, the resilience of the zonula fibres, by which the capsular bag is suspended elastically from the ciliary muscle, also shows considerable fluctuations among individuals. Finally, for a large part of the patients it is to be expected that an opacification of the posterior capsule of the lens will occur after a cataract operation (secondary cataract). This opaque part must then be removed, for example with a laser, which once again drastically changes the mechanical properties of the capsular bag.
The object of this present invention is to make an intraocular lens available which changes its position in an axial direction on contraction of the ciliary muscle. The postoperative shrinkage of the capsular bag, the variation in the resilience of the zonula fibres and a later removal of the posterior, central part of the capsule (capsulotomy) are intended not to influence the function of the accommodation process substantially.
The object is solved by the invention in accordance with claim 1. The intraocular implant, to be inserted into the capsular bag in the generally known manner, contains an artificial lens in generally known technology at its center permanent magnets on its peripheral part which are arranged in a circle, with the optical axis of the eye as the normal of the circle (hereinafter called xe2x80x9cthe inner magnetsxe2x80x9d). Opposite these inner magnets, permanent magnets are also fastened to the sclera in a circle lying further back, outside, the normal of the circle of which is once again the optical axis of the eye (hereinafter called xe2x80x9cthe outer magnetsxe2x80x9d). The inner and outer magnets are polarised in such a manner that they repel one another reciprocally, and are aligned geometrically in such a manner that this repulsion exercises a force directed towards the front of the capsular bag, and thus towards the intraocular lens located therein.